Taxol is a compound isolated from the stem bark of the western yew. It is the first compound of this type to have anti-leukemic and tumor inhibitory properties. Taxol has demonstrated a broad spectrum of activity against murine and human solid tumor and leukemic cell lines in studies by the NCI Division of Cancer Treatment. The purpose of this phase I study is to determine the maximum tolerable dose of Taxol given as a continuous hour infusion every week, as well as to determine the antileukemic activity of Taxol. study will include patients with leukemia (ALL, ANLL, and CML) and M3 marrow under age 21. The patients disease must be considered refractory or be in relapse after achieving with conventional therapy and other therapies of higher priority.